Three years of retrospective studies with self-quitters have indicated that such research can yield significant data on the complex processes and stages of change involved in the successful cessation of smoking. Work to date has generated a revolving door model of change that has discriminated processes of change used by self-quitters from those used by subjects in formalized treatments. Self-quitters revolve through a cyclical series of stages an average of three times prior to permanently exiting from their habit of smoking. Different change processes are used to progress through each of the stages and subjects differing on age, sex and SES use particular processes more than others. The objective of the proposed research is to advance our present understanding of the processes used by self-quitters to enter the revolving door of change, to progress through each stage and to exit into a non-smoking life-style. The initial retrospective phase of the research would interview and assess a sample of 1000 subjects representing each of four critical stages of change and smokers not currently intending to quit. These same subjects would be assessed every six months for three years in a longitudinal phase designed to more accurately determine the behavioral, cognitive and systems changes involved in quitting smoking. In the second year a comprehensive outcome experiment will test the hypotheses that self-quitters can be as successful as subjects in traditional formalized treatments and that these treatments can be improved through the application of data from self-quitters. In the third year a controlled experiment will test the hypothesis that the dissemination of information from the longitudinal work can improve the success rate of smokers who quit on their own. The importance of providing adequate data on these issues stems from the high rate of smoking that continues even though a majority of smokers are aware of increased risks of cancer and other life-endangering illnesses related to smoking. National surveys indicate that 60% of smokers have tried to quit but failed. Data from successful self-quitters can suggest more effective cancer control programs for the cessation of smoking.